engineering

Nevada–Texas–Utah retort

Nevada–Texas–Utah retort is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Nevada–Texas–Utah retort rather than just read about it. In short: The Nevada–Texas–Utah retort process (also known as NTU, Dundas–Howes or Rexco process) was an above-ground shale oil extraction technology to produce shale oil, a type of synthetic crude oil. It heated oil shale in a sealed vessel (retort) causing its decomposition into shale oil, oil shale gas and spent residue.

Key takeaways

Nevada–Texas–Utah retort belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Nevada–Texas–Utah retort to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Nevada–Texas–Utah retort from memory before moving on to harder problems.

Reference excerpt

The Nevada–Texas–Utah retort process (also known as NTU, Dundas–Howes or Rexco process) was an above-ground shale oil extraction technology to produce shale oil, a type of synthetic crude oil. It heated oil shale in a sealed vessel (retort) causing its decomposition into shale oil, oil shale gas and spent residue. The process was developed in the 1920s and used for shale oil production in the United States and in Australia. The process was simple to operate; however, it was ceased from the operation because of a small capacity and labor extensiveness.

History The NTU retort was a successor of the 19th-century coal gasification retorts and it is considered as a predecessor of the gas combustion retort and the Paraho processes. It was invented and patented by Roy C. Dundas and Raymond T. Howes in 1923. The process was improved by David Davis and George Wightman Wallace, a consulting engineer of the NTU Company. In 1925, the NTU Company built a test plant at Sherman Cut near Casmalia, California. In 1925–1929, the process was tested by the United States Bureau of Mines in the Oil Shale Experiment Station at Anvil Point in Rifle, Colorado. Retorting was carried out from 17 January to 28 June 1927. The plant was dismantled when work was terminated in June 1929. One of the leading technologist involved in this stage was Lewis Cass Karrick, an inventor of the Karrick process. In 1946–1951, two pilot plants with nominal capacities of 40 tons of raw oil shale were located at the same location. More than 12,000 barrels of shale oil was produced during this period. During the World War II, three NTU retorts were operated at Marangaroo, New South Wales, Australia. Almost 500,000 barrels of shale oil was produced by these retorts by retorting local torbanite.

Retort The NTU retort was a vertical downdraft retort, which used internal combustion to generate heat for an oil shale pyrolysis (chemical decomposition). The retort was designed as a steel cylinder, lined with fire bricks. At the top it was equipped with an air supply pipe and at the bottom it was equipped with an exhaust pipe. The batch of crushed oil shale was loaded from the top; after that the retort was sealed. To start the pyrolysis process the fuel gas was ignited at the top of retort, and air injection into the retort started. The supply of fuel gas stopped after the upper quarter of the oil shale batch started to burn. At the same time the air injection continued bringing temperature in the burning part to about 1,500 °F (820 °C). The heated gas caused a pyrolysis on the lower part of oil shale and produced shale oil and oil-shale gas are escaped from the retort through exhaust pipe at the bottom of retort. The pyrolysis occurred at the temperature about 800 °F (430 °C). By time-being, the combustion zones moved downward, and the char (semi-coke) produced as a solid residue of pyrolysis, ignited to burn as additional fuel for combustion. This caused the pyrolysis zone to move downward to the lower parts of retort. After combustion zone reached to the bottom of retort, air injection was stopped to stop combustion. After burning of char, the shale oil production ceased and only spent oil shale ash remained in the retort. The bottom of retort could opened for removal of the oil shale ash after retorting process. Operating the NTU retort with nominal capacity of 40 ton of raw oil shale, the full process cycle took about 40 hours. The shale oil yield varied from 80% to 85% of Fischer assay.

Advantages and disadvantages The advantage of the NTU retort process was simple design, simple operation, and limited need for external fuel. It was suitable for processing of wide variety of oil shales. The disadvantage of this process was a batch mode of operation not allowing continuous retorting, and therefore having small capacity being labor extensive at the same time. The process also had a relatively low oil yield and it required cooling water.

See also Alberta Taciuk process Petrosix Kiviter process Galoter process TOSCO II process Fushun process Superior multimineral process Pumpherston retort

References

Worked examples

Example 1 — a first encounter with Nevada–Texas–Utah retort

Start with the simplest possible case. Write down what Nevada–Texas–Utah retort claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Nevada–Texas–Utah retort before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Nevada–Texas–Utah retort ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Nevada–Texas–Utah retort

In research: Nevada–Texas–Utah retort appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Nevada–Texas–Utah retort in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Nevada–Texas–Utah retort is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fuels infrastructure in the United States, Oil shale technology, Petroleum in the United States, so understanding it makes those chapters shorter.
In everyday life: Look for Nevada–Texas–Utah retort outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Nevada–Texas–Utah retort in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nevada–Texas–Utah retort means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Nevada–Texas–Utah retort out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nevada–Texas–Utah retort in simple terms?

Why does Nevada–Texas–Utah retort matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Nevada–Texas–Utah retort?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Nevada–Texas–Utah retort.